For the past several years, the producers of raw agricultural commodities have suffered from low prices and surpluses because of reduced demand and increased world supplies (ESCOP. 1988. Enhanced research agenda for value added food and non-food uses of agricultural products. The Experiment Station Committee on Organization and Policy. Washington, D.C.). Recently efforts have been made to reverse the trend by converting agricultural commodities into value-added products. For example, corn was grown in the 1970's mainly for livestock feeds, but today it is being used increasingly to produce high-fructose corn syrup, fuel-alcohol and other non-food products (Wolf, D. Finger Lakes Times, Geneva, N.Y.: Jan. 23, 1989).
Lactic acid is produced commercially by the fermentation of glucose, molasses or cheese whey with homofermentative lactic acid bacteria (Prescott, S. C. et al, 1959, Industrial Microbiology, 3rd ed. New York: McGraw-Hill). Wart et al, U.S. Pat. No. 2,132,712 have produced dextro-lactic acid by fermentation of glucose solutions with Rhizopus oryzae.
It is desired to produce a L(+)-lactic acid in high yield and purity in a direct one-step fermentation from a readily renewable biomass. L(+)-lactic acid and its salts will find increased use as components of foods, pharmaceuticals and as monomer in the preparation of biodegradeable polymers.
The instant invention relates to the simultaneous saccharification and fermentation of corn to L(+)-lactic acid in high yield.